Bagley's sprain is in the middle of his foot, the team said. He left Thursday's overtime loss to the Minnesota Timberwolves with the injury.
Bagley missed time earlier this season because of a broken thumb.
In his second season, Bagley is averaging 13.7 points in nine games. Last year, the former No. 2 overall pick averaged 14.9 points and 7.6 rebounds in 62 games.